The present invention relates to a needle module for a tufting machine. A plurality of needles are mounted in the module each comprising a shank having an eye at one end, and a mounting portion at the opposite end mounted in the module and a yarn feed groove extending from the eye towards the mounting portion. Such modules are widely used in the art.
One problem with needles of this type is that, as the yarn is fed into the groove at an angle, friction between the yarn and the backing material causes an increase in yarn tension which causes problems such as stretching of the backing material, unevenness in the pile height, an increased power requirement to achieve needle penetration and an increase in loose fibers.
In an attempt to overcome these problems, a thread-feeding element has been proposed in EP-A-0882831. This thread-feeding element is essentially a guide which ensures that the yarn enters the top of the yarn feed groove and is then fed directly down the length of the needle thereby greatly reducing the contact between the yarn and backing material.
However, for various reasons, the only example which has proved practical is the double-eyed cranked needle shown in FIG. 4 of EP-A-0882831. Even with this design, there a number of disadvantages that have limited the applications of this needle. The complex structure of the needle makes it expensive to produce. The presence of the eye towards the upper end of the needle weakens the needle. The crank configuration limits the pitch (gauge) on in-line needle bars and modules. As the double-eyed configuration makes the needle difficult to thread, single staggered needle bars and modules are not practical. Thus, the needle has been used in only a limited number of applications.
A similar arrangement proposed by the applicant has a needle cranked such a way as to provide direct access to the top of the yarn feed groove. However, this also suffers from high manufacturing costs and reduced stability at the 90xe2x80x2 bend and is not suitable for dual sliding needle bar machines due to threading difficulties.
A further attempt to overcome these problems is disclosed in our earlier application WO 01/77431 and U.S. Pat. No. 09/614,002 U.S. Pat. No. 6,339,995. This discloses a lateral rod extending through the top portion of the needles. This solution has proved successful under many circumstances, but can be difficult to implement in finer gauge machines.
According to the present invention, there is provided a needle module for a tufting machine having a body in which a plurality of needles are mounted, each needle comprising a shank having an eye at one end, a mounting portion at the opposite end which is mounted in the module body and a yarn feed groove extending from the eye towards the mounting portion; characterized by a rod mounted on and spaced from the module body and extending across the module body transversely to the needles.
By moving the transverse rod from the top of the needles to the needle module, a number of advantages arise. Firstly, the assembly is easier to manufacture as it is no longer necessary to make holes in the top of the needles which must then be aligned to receive the rod. Also, for any module, the yarn passing around the rod will then fan out so that it can reach particularly the outermost needles. By moving the rod higher up onto the needle module, the angle at which the yarn is fanned out is decreased, so that the yarn to the outermost needles of a module enters the yarn feed groove at a shallow angle and therefore flows more freely down the yarn feed groove. Also, when the rod is passed through the top of the needles, it is necessary for it to project from the end most needle in a module. This projecting part is required to abut the end most needle in an adjacent module to guide the yarn into that needle. In practice, difficulties arise with aligning this projecting part with the adjacent needle. With the present invention, as the yarns for a particular module pass around the rod without also having to pass between adjacent needles at this stage, all of the yarns for a particular module can be guided by the rod without it needing to project from the module. Any such alignment problems are therefore eliminated.
Preferably, the rod is mounted on a pair of bosses extending from opposite ends of a face of the housing. The rod can be fixed to the bosses, or may be formed as an integral part of the needle module body.
Preferably, the boss at the end of the module having a needle with an outwardly facing yarn feed groove has a face which faces the other boss, this face having a taper which tapers away from the other boss towards the needles. This provides a straighter path for the yarn into the yarn feed groove of the end needle.